Alkyl mercaptans are useful in the manufacture of alkyl sulfonic acids which are used to make detergents such as those described in U.S. Pat. No. 2,142,162 and U.S. Pat. No. 2,187,339. Alkyl mercaptans are readily converted to sulfonic acid by oxidation. Oxidation of mercaptans with nitric acid is described in Werniz, U.S. Pat. No. 2,142,162; U.S. Pat. No. 2,187,338 and U.S. Pat. No. 2,187,339. Proell, et al U.S. Pat. No. 2,505,910 disclose a method of oxidizing mercaptans to sulfonic acids using oxygen in combination with nitrogen oxides. Schreyer et al U.S. Pat. No. 4,052,445 discloses an oxidation process using hydrogen peroxide as the oxidant.
Alkyl mercaptans had been made by the reaction of hydrogen sulfide with olefins. Olin, U.S. Pat. No. 2,434,510 describes a process for reacting hydrogen sulfide and olefin by passing the mixture containing a Lewis Acid catalyst through a tubular reactor or by a batch method in which hydrogen sulfide is added to a reactor containing the olefin and catalyst.
Eaton et al, U.S. Pat. No. 2,443,852 describes a similar process carried out under pressure in which the olefin, hydrogen sulfide and catalyst are concurrently mixed in the liquid phase and then the hydrogen sulfide is vaporized to cool the reaction mixture.
Although the reaction of hydrogen sulfide with olefin does yield alkyl mercaptans, it also forms dialkyl sulfides by reaction of an alkyl mercaptan with olefin. Alkyl mercaptans are readily oxidized to sulfonic acid but dialkyl sulfides are not. Therefore, a need exists for a process that will make alkyl mercaptans in high yield while minimizing the formation of dialkyl sulfides.